Most synthetic fibers and natural fibers have a static electricity due to friction between fibers or between fiber and skin. The static electricity causes various problems such as fire, skin trouble, discomfort, etc. not only in daily life but also in industrial field.
In order to solve the problem of static electricity generation in the fiber, the fiber is treated with an antistatic agent, and the various methods for imparting conductivity to fibers have been developed.
A method of treating fibers using an antistatic agent is inexpensive and simple in process, but there is a disadvantage that the antistatic effect is significantly reduced during washing and long-term use.
As a method for imparting conductivity to fibers, there are a method of mixing carbon black or metal powder having conductivity with a polymer, and then spinning it to give a fiber; a method of plating metal on the surface of a fiber; a method of depositing a metal powder in a hole existing on the surface of a fiber, and the like.
A method for producing a conductive fiber by mixing carbon black or a metal powder with a polymer cannot form uniform mixture of carbon black or metal powder and the polymer, and the strength, elongation and thermal properties of the fiber are significantly deteriorated during the spinning.
An electroless plating method is widely used as a method of plating a metal on a fiber surface. In the electroless plating method, in order to improve the adhesion between the fiber and the metal film, a process of forming wrinkles on the surface, a cleaning process using strong acid, and the like are necessary. Therefore, the fiber processing process is very complicated, and it is difficult to expect the inherent physical properties of the produced conductive fibers.
In method of depositing the metal powder in the pores present on the fiber surface, the fiber has to include pores larger than the particles of metal. Therefore, porous fibers with large diameter pores should be prepared during fiber production. A unique spinning process is required to fabricate the porous fibers. And the mechanical, chemical and thermal properties of the fibers are significantly degraded.
In order to solve the above problems, various techniques for producing conductive fibers have been developed by forming metal compound on the surface of a fiber.
U.S. Pat. No. 4,336,028 discloses a method for producing a conductive fiber by treating a composition comprising a divalent copper ion, a reducing agent and sulfur-containing compound with the acrylic fiber, wherein a reducing agent reduces divalent copper ion into monovalent copper ion and sulfur-containing compound forms copper sulfide by reacting with monovalent copper ion.
U.S. Pat. No. 4,378,776 discloses a process for preparing a conductive fiber coated with copper sulfide by treating a composition comprising copper compounds, reducing agents, sulfur compounds and pH adjusting agents with fiber.
Also, Korean Patent No. 10-1984-0002108 discloses a conductive fiber manufactured by treating at least one kind of fiber selected from a polyamide-fibers, polyester fibers, rayon fibers, copper ammonium fibers, animal fibers and vegetable fibers with composition comprising a divalent copper ion, a reducing agent capable of reducing divalent copper ions to monovalent copper ions, and a compound capable of releasing at least one sulfur component.
However, the above documents disclose that copper sulfide is coordinated to fibers to impart conductivity. The color of the fiber changes drastically because copper sulfide is desorbed during repeated washing or prolonged use. And washing resistance, durability, moisture resistance, alkali resistance, and the like are sharply reduced.
In addition, the conductive fibers cannot be widely used in the fields of apparel, industrial and military field because antibacterial, deodorant, far-infrared radiation, wound healing, heat storage and insulation, electromagnetic shielding, and static electricity property are inferior.